Zoom lens barrel assembly

ABSTRACT

A zoom lens barrel assembly including: a first zoom ring comprising a first protrusion; a guide ring disposed around the first zoom ring comprising a first guide slot through which the first protrusion passes, and a second guide slot; a second zoom ring comprising a second protrusion, and movable in an axial direction; a first cylinder comprising a guide groove into which the second protrusion inserts, and a third protrusion passing through the second guide slot, and disposed between the first and second zoom rings; a second cylinder disposed around the guide ring comprising a fourth protrusion, a first groove portion into which the first protrusion inserts, and a second groove portion into which the third protrusion inserts, and supporting the first zoom ring and the first cylinder; and an external cylinder disposed around the second cylinder and comprising a third groove portion into which the fourth protrusion inserts.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the priority benefit of Korean PatentApplication No. 10-2011-0012471, filed on Feb. 11, 2011, in the KoreanIntellectual Property Office, the entirety of which is incorporatedherein by reference.

BACKGROUND

1. Field of the Invention

The invention relates to a zoom lens barrel assembly, and moreparticularly to, a zoom lens barrel assembly that implements a highmagnification zooming function while having a small thickness or shortlength when the zoom lens barrel assembly is accommodated in a camera.

2. Description of the Related Art

An optical system having various focal distances is realized when a zoomlens barrel assembly that is able to adjust distances between lensgroups is mounted in a camera. The zoom lens barrel assembly can be usedto change the optical system of the camera between a wide angle lenssystem or a telephoto lens system so that a user can performphotographing at various viewing angles without moving.

Relative positions of barrels that support lens groups must be changedto adjust distances between the lens groups. For example, fivemagnification zooming may be implemented using a 3-step zoom lens barrelassembly having 3 relatively movable barrels. However, suchimplementation increases the number of parts in the 3-step zoom lensbarrel assembly.

When no photographing is performed, elements of a zoom lens barrelassembly may be accommodated in a camera. In this regard, a thickness orlength of the zoom lens barrel assembly may be minimized in order torealize a compact camera having a small thickness to meet market demand.

Recently, a compact camera may be required to implement, for example, ahigh-performance five magnification zooming function, and thus a zoomlens barrel assembly in the camera must perform a high-performancezooming function while having a small thickness or short length.However, 3 relatively movable barrels must be disposed in the 3-stepzoom lens barrel assembly to implement five magnification zooming. Thus,reduction of a minimum thickness of the zoom lens barrel assembly isdifficult when the 3-step zoom lens barrel assembly is accommodated.

SUMMARY

The invention provides a zoom lens barrel assembly that implements ahigh-magnification zooming function while having a small thickness orshort length when the zoom lens barrel assembly is accommodated withinan optical device such as a camera.

The invention also provides a zoom lens barrel assembly having a reducednumber of parts.

The invention also provides a zoom lens barrel assembly that implementsa high-magnification zooming function while having a small thickness orshort length and a reduced number of relatively moving barrels.

According to an aspect of the invention, there is provided a zoom lensbarrel assembly including: a first zoom ring for supporting a first lensgroup and comprising a first protrusion protruding outward; a guide ringcomprising a first guide slot extending in an axial direction, throughwhich the first protrusion passes, and a second guide slot extending ina circumferential direction, and disposed around the first zoom ring; asecond zoom ring for supporting a second lens group, comprising a secondprotrusion protruding outward, and movably disposed in the axialdirection with respect to the first zoom ring; a first cylindercomprising a second zoom ring guide groove formed in an inner wallsurface of the first cylinder into which the second protrusion isinserted and a third protrusion protruding outward so as to pass throughthe second guide slot, and disposed between the first zoom ring and thesecond zoom ring so as to rotate and move in the axial direction; asecond cylinder comprising a fourth protrusion protruding outward,rotatably disposed around the guide ring, comprising a first grooveportion into which the first protrusion passing through the first guideslot is inserted, and a second groove portion into which the thirdprotrusion passing through the second guide slot is inserted, andmovably supporting the first zoom ring and the first cylinder; and anexternal cylinder comprising a third groove portion into which thefourth protrusion is inserted, and disposed around the second cylinderto rotatably support the second cylinder.

The zoom lens barrel assembly may further include: a guide portiondisposed guiding a motion of the second zoom ring in the axial directionwhile the first cylinder rotates.

The second zoom ring may include a cutting portion extending in theaxial direction in the outside thereof, and the guide portion isdisposed between the second zoom ring and the first cylinder, coupled tothe cutting portion, and guides a motion of the second zoom ring in theaxial direction.

The second zoom ring may include a guide slot extending in the axialdirection, and the guide portion is pin-shaped extending in the axialdirection, inserted into the guide slot, and guides a motion of thesecond zoom ring in the axial direction.

The second cylinder may include a gear disposed around the secondcylinder and extending in the circumferential direction, and the zoomlens barrel assembly may include a driving portion coupled to the gearand for generating a driving force used to rotate the second cylinder.

The zoom lens barrel assembly may further include: a base fixed to theexternal cylinder; and an optical device disposed in the base so thatthe optical device corresponds to the first lens group and the secondlens group.

The zoom lens barrel assembly may further include: a third lens groupdisposed between the optical device and the second lens group; a thirdzoom ring for supporting the third lens group and moving in the axialdirection; and a focus driving unit coupled to the third zoom ring andgenerating a driving force.

The second groove portion may extend in the axial direction, and thesecond guide slot may include a sustaining portion extending in thecircumferential direction along or parallel to a boundary of one end ofthe guide ring and sustaining a position of the first cylinder in theaxial direction with respect to the guide ring, and a changing portioninclined from an end portion of the sustaining portion toward a boundaryof another end of the guide ring and for changing the position of thefirst cylinder in the axial direction with respect to the guide ring.

The first groove portion may include a first inclination portioninclined from a boundary of one end of the second cylinder toward aboundary of another end thereof, extending in the circumferentialdirection, and moving the first zoom ring forward in the axial directionwith respect to the second cylinder, and a second inclination portioninclined from an end portion of the first inclination portion toward theboundary of the one end, extending in the circumferential direction, andmoving the first zoom ring backward in the axial direction with respectto the second cylinder.

The second zoom ring guide groove may include a rectilinear portionrectilinearly extending in the axial direction from a boundary of oneend of the first cylinder to a boundary of another end thereof, abackward inclination portion inclined from an end portion of therectilinear portion toward the boundary of the one end of the firstcylinder, extending in the circumferential direction, and moving thesecond zoom ring forward in the axial direction with respect to thefirst cylinder, and a forward inclination portion inclined from thebackward inclination portion toward the boundary of the other end of thefirst cylinder, extending in the circumferential direction, and movingthe second zoom ring forward in the axial direction with respect to thefirst cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the invention will becomemore apparent by describing in detail exemplary embodiments thereof withreference to the attached drawings in which:

FIG. 1 is a perspective view of a zoom lens barrel assembly, accordingto an embodiment of the invention;

FIG. 2 is a cross-sectional perspective view of the zoom lens barrelassembly of FIG. 1, according to an embodiment of the invention;

FIG. 3 is an exploded perspective view of the zoom lens barrel assemblyof FIG. 1, according to an embodiment of the invention;

FIG. 4 is a cross-sectional view of the zoom lens barrel assembly ofFIG. 1, according to an embodiment of the invention;

FIG. 5 is a cross-sectional view of the zoom lens barrel assembly ofFIG. 4 that is adjusted at a wide-angle lens and performs zooming,according to an embodiment of the invention; and

FIG. 6 is a cross-sectional view of the zoom lens barrel assembly ofFIG. 4 that is adjusted at a telephoto-angle lens and performs zooming,according to an embodiment of the invention.

DETAILED DESCRIPTION

Hereinafter, the invention will be described more fully with referenceto the accompanying drawings, in which exemplary embodiments of theinvention are shown.

FIG. 1 is a perspective view of a zoom lens barrel assembly according toan embodiment of the invention. Referring to FIG. 1, the zoom lensbarrel assembly unfolds in 2 steps and performs a 5-magnificationoptical zooming function.

The zoom lens barrel assembly includes an external cylinder 80 installedin a base 90, a first zoom ring 20 movably disposed in the externalcylinder 80, and a second cylinder 70. The second cylinder 70 isdisposed to move forward or backward from the external cylinder 80 in anaxial direction (in a Z direction). The first zoom ring 20 is disposedto move forward or backward from the second cylinder 70 in the axialdirection.

The zoom lens barrel assembly can perform a zooming function because thefirst zoom ring 20 and the second cylinder 70, which move from theexternal cylinder 80 fixed in the base 90 in the axial direction, areunfolded in 2 steps. Thus, a whole thickness or length of the zoom lensbarrel assembly can be reduced when the first zoom ring 20 and thesecond cylinder 70 are accommodated in the external cylinder 80, therebyeasily implementing a small-sized and thin-shaped camera.

A driving unit 5 that generates a driving force for performing thezooming function and a focus driving unit 7 that generates a drivingforce for performing a focusing function are disposed in exteriorsurfaces of the base 90 and the external cylinder 80.

FIG. 2 is a cross-sectional perspective view of the zoom lens barrelassembly of FIG. 1, according to an embodiment of the invention. FIG. 3is an exploded perspective view of the zoom lens barrel assembly of FIG.1, according to an embodiment of the invention.

Referring to FIGS. 2 and 3, the zoom lens barrel assembly comprises thefirst zoom ring 20 that supports a first lens group 10, a guide ring 30disposed around the first zoom ring 20, a second zoom ring 50 thatsupports a second lens group 40, a first cylinder 60 disposed betweenthe first zoom ring 20 and the second zoom ring 50, a second cylinder 70that is disposed around the guide ring 30, and movably supports thefirst zoom ring 20 and the first cylinder 60, and an external cylinder80 that is disposed around the second cylinder 70.

The external cylinder 80 acts as a support structure that maintains afixed state in the zoom lens barrel assembly.

When the zoom lens barrel assembly operates and performs the zoomingfunction, the first zoom ring 20 protrudes forward in the axialdirection (in the Z direction) with respect to the second cylinder 70.The first zoom ring 20 has a cylindrical shape, supports the first lensgroup 10, and comprises a first protrusion 21 that protrudes to theoutside of the first zoom ring 20. The first lens group 10 is coupled toa front of the first zoom ring 20 using a lens support portion 11disposed therebetween. The first zoom ring 20 moves forward or backwardin the axial direction, and thus a position of the first lens group 10with respect to the axial direction can be adjusted.

The guide ring 30 has a hollow cylindrical shape and is disposed outsidethe first zoom ring 20. An inner wall surface of the guide ring 30comprises a first guide slot 31 that rectilinearly extends in the axialdirection, through which the first protrusion 21 of the first zoom ring20 passes, and a second guide slot 32 that is inclined in the axialdirection and extends in the circumferential direction. The first guideslot 31 guides a movement of the first protrusion 21 to cause the firstzoom ring 20 to perform a rectilinear motion in the axial direction.

A rectilinear guide protrusion 35 that protrudes to the outside of theguide ring 30 is screwed to a rectilinear groove portion 85 thatrectilinearly extends in the inner wall surface of the external cylinder80 in the axial direction. Thus, although the guide ring 30 is disposedin the second cylinder 70, the guide ring 30 does not rotate withrespect to the external cylinder 80 and rectilinearly moves in the axialdirection, together with the second cylinder 70, when the secondcylinder 70 rotates with respect to the external cylinder 80.

The first cylinder 60 is disposed in the guide ring 30. The firstcylinder 60 has a hollow cylindrical shape, comprises a secondprotrusion 61 that protrudes to the outside of the first cylinder 60,and moves in the axial direction while rotating. The second protrusion61 of the first cylinder 60 is inserted into the second guide slot 32 ofthe guide ring 30 so that the guide ring 30 can movably support thefirst cylinder 60.

An exterior diameter of the first cylinder 60 is smaller than aninterior diameter of the first zoom ring 20. Thus, when the first zoomring 20 and the first cylinder 60 are guided by the guide ring 30 andmove in the axial direction, the first cylinder 60 can be inserted intothe first zoom ring 20.

The second zoom ring 50 is movably disposed in the first cylinder 60.The second zoom ring 50 supports the second lens group 40. The secondlens group 40 is coupled to the second zoom ring 50 using a lens supportportion 41 disposed therebetween.

The second zoom ring 50 comprises a third protrusion 51 that protrudesto the outside of the second zoom ring 50. The third protrusion 51 ofthe second zoom ring 50 is inserted into a second zoom ring guide groove62 formed in an inner wall surface of the first cylinder 60, and thusthe rotation of the first cylinder 60 causes the third protrusion 51 tobe guided by the second zoom ring guide groove 62, and the second zoomring 50 to rectilinearly move in the axial direction.

A cutting portion 52 that extends in the axial direction is formed in anexterior wall surface of the second zoom ring 50 in order to prevent thesecond zoom ring 50 from rotating, and to rectilinearly move in theaxial direction. A guide portion 55 that is coupled to the cuttingportion 52 and guides a motion of the second zoom ring 50 in the axialdirection is disposed between the second zoom ring 50 and the firstcylinder 60. The guide portion 55 is screwed to a guide portion guidegroove 64 that extends in the inner wall surface of the first cylinder60 in the circumferential direction, and thus the first cylinder 60rotates while the guide portion 55 guides the cutting portion 52. Theguide portion 55 is coupled to the cutting portion 52, thereby fixing aposition of the second zoom ring 50 in the circumferential direction ofthe guide portion 55.

As described above, because the rotation of the first cylinder 60 causesthe second zoom ring 50 to move in the first cylinder 60 in the axialdirection, which changes a relative position of the second lens group 40in the axial direction with respect to the first lens group 10, thezooming function is realized.

Although the cutting portion 52 and the guide portion 55 are used toguide the second zoom ring 50 to rectilinearly move in the axialdirection without rotating during the rotation of the first cylinder 60in the present embodiment, the invention is not limited thereto. Forexample, a pin extending in the axial direction and a guide slotextending in the second zoom ring 50 in the axial direction, throughwhich the pin is inserted, may be used to guide the second zoom ring 50to rectilinearly move in the axial direction during the rotation of thefirst cylinder 60.

The second cylinder 70 is rotatably disposed around the guide ring 30.The second cylinder 70 has a hollow cylindrical shape and comprises afourth protrusion 71 that protrudes to the outside of the secondcylinder 70. An inner wall surface of the second cylinder 70 comprises afirst groove portion 72 to which the first protrusion 21 passing throughthe first guide slot 31 of the guide ring 30 is screwed, and a secondgroove portion 73 to which the third protrusion 61 passing through thesecond guide slot 32 of the guide ring 30 is screwed. Thus, the secondcylinder 70 movably supports the first zoom ring 20 and the firstcylinder 60 and guides a movement of the first zoom ring 20 and thefirst cylinder 60.

The first groove portion 72 comprises a first inclination portion 72 athat is inclined from a boundary 78 of one end of the second cylinder 70to a boundary 79 of another end thereof and extends in thecircumferential direction, and a second inclination portion 72 b that isinclined from an end portion of the first inclination portion 72 a tothe boundary 78 and extends in the circumferential direction.

The first inclination portion 72 a performs a function of moving thefirst zoom ring 20 forward in the axial direction with respect to thesecond cylinder 70. The second inclination portion 72 b performs afunction of moving the first zoom ring 20 backward in the axialdirection with respect to the second cylinder 70.

A third groove portion 82 is formed in an inner wall surface of theexternal cylinder 80. The second cylinder 70 is disposed in the externalcylinder 80, and the fourth protrusion 71 of the second cylinder 70 isscrewed to the third groove portion 82, so that the external cylinder 80rotatably supports the second cylinder 70. Because the fourth protrusion71 is guided by the third groove portion 82 of the external cylinder 80,rotation of the second cylinder 70 causes the second cylinder 70 to movein the axial direction.

A gear 75 that extends in the circumferential direction is installed onan exterior wall surface of the second cylinder 70. The driving portion5 of FIG. 1 is connected to the gear 75, and thus a driving forcegenerated by the driving portion 5 is transferred to the gear 75, andthe second cylinder 70 rotates with respect to the external cylinder 80.

The base 90 is coupled to an end portion of the external cylinder 80. Anoptical device 91 that converts image light transmitted through thefirst lens group 10 and the second lens group 40 into an electricalsignal is disposed in the base 90. The optical device 91 is disposed ata position corresponding to the first lens group 10 and the second lensgroup 40.

A third lens group 100 is disposed between the optical device 91 and thesecond lens group 40. The third lens group 100 can move in the axialdirection so as to realize a focusing function.

The third lens group 100 is supported by a third zoom ring 110. Thefocus driving unit 7 is coupled to the third zoom ring 110. The thirdzoom ring 110 can move in the axial direction by a driving forcegenerated by the focus driving unit 7, and thus a position of the thirdlens group 100 in the axial direction can be adjusted.

The second guide slot 32 comprises a sustaining portion 32 a thatextends in the circumferential direction along a boundary 38 of one endof the guide ring 30, and a changing portion 32 b that is inclined froman end portion of the sustaining portion 32 a to a boundary 39 ofanother end of the guide ring 30 and extends in the circumferentialdirection.

The sustaining portion 32 a performs a function of sustaining a positionof the first cylinder 60 in the axial direction with respect to theguide ring 30 during an initial predetermined section in which thesecond cylinder 70 starts rotating. The changing portion 32 b performs afunction of changing the position of the first cylinder 60 in the axialdirection with respect to the guide ring 30.

The second zoom ring guide groove 62 formed in the inner wall surface ofthe first cylinder 60 comprises a rectilinear portion 62 a thatrectilinearly extends in the axial direction from a boundary 68 of oneend of the first cylinder 60 toward a boundary 69 of another endthereof, a backward inclination portion 62 b that is inclined from anend portion of the rectilinear portion 62 a toward the boundary 68 ofthe one end of the first cylinder 60 and extends in the circumferentialdirection, and a forward inclination portion 62 c that is inclined fromthe backward inclination portion 62 b toward the boundary 69 of theother end of the first cylinder 60 and extends in the circumferentialdirection.

The rectilinear portion 62 a performs a function of moving the secondzoom ring 50 forward in the axial direction with respect to the firstcylinder 60. The backward inclination portion 62 b performs a functionof moving the second zoom ring 50 backward in the axial direction withrespect to the first cylinder 60. The forward inclination portion 62 cperforms a function of moving the second zoom ring 50 forward in theaxial direction with respect to the first cylinder 60.

FIG. 4 is a cross-sectional view of the zoom lens barrel assembly ofFIG. 1, according to an embodiment of the invention. FIG. 5 is across-sectional view of the zoom lens barrel assembly of FIG. 4 that isadjusted at a wide-angle lens and performs zooming, according to anembodiment of the invention. FIG. 6 is a cross-sectional view of thezoom lens barrel assembly of FIG. 4 that is adjusted at atelephoto-angle lens and performs zooming, according to an embodiment ofthe invention.

When the zoom lens barrel assembly is accommodated in a camera or otheroptical device, all of the second cylinder 70, the first cylinder 60,and the first zoom ring 20 are accommodated in the external cylinder 80.The zoom lens barrel assembly adopts a 2-step barrel structure in whichthe second cylinder 70 and the first zoom ring 20 protrude in the axialdirection with respect to the external cylinder 80, and thus having asmall thickness or short length when the zoom lens barrel assembly isaccommodated in an optical device such as a camera, while implementing ahigh-magnification zooming function.

If the driving portion 5 operates and generates a driving force, thesecond cylinder 70 rotates with respect to the external cylinder 80. Therotational force of the second cylinder 70 is transferred to the firstprotrusion 21 of the first zoom ring 20 screwed to the first grooveportion 72 and to the second protrusion 61 of the first cylinder 60screwed to the second groove portion 73.

The guide ring 30 does not rotate with respect to the external cylinder80 and rectilinearly moves in the axial direction, together with thesecond cylinder 70, when the second cylinder 70 rotates with respect tothe external cylinder 80. Therefore, the first zoom ring 20 canrectilinearly move in the axial direction according to the firstprotrusion 21 passing through the first guide slot 31 of the guide ring30. The first cylinder 60 can rotate with respect to the guide ring 30and move in the axial direction according to the second protrusion 61passing through the second guide slot 32 of the guide ring 30.

Relative positions of the first lens group 10 and the second lens group40 are changed owing to the rotation of the second cylinder 70, and thusthe zoom lens barrel assembly can be adjusted at a wide-angle lens asshown in FIG. 5 or at a telephoto-angle lens as shown in FIG. 6.

The embodiments described herein may comprise a memory for storingprogram data, a processor for executing the program data, a permanentstorage such as a disk drive, a communications port for handlingcommunications with external devices, and user interface devices,including a display, keys, etc. When software modules are involved,these software modules may be stored as program instructions orcomputer-readable codes, which are executable by the processor, on anon-transitory or tangible computer-readable media such as read-onlymemory (ROM), random-access memory (RAM), a compact disc (CD), a digitalversatile disc (DVD), magnetic tapes, floppy disks, optical data storagedevices, an electronic storage media (e.g., an integrated circuit (IC),an electronically erasable programmable read-only memory (EEPROM),and/or a flash memory), a quantum storage device, a cache, and/or anyother storage media in which information may be stored for any duration(e.g., for extended time periods, permanently, brief instances, fortemporarily buffering, and/or for caching of the information). Thecomputer-readable recording medium can also be distributed overnetwork-coupled computer systems (e.g., a network-attached storagedevice, a server-based storage device, and/or a shared network storagedevice) so that the computer-readable code may be stored and executed ina distributed fashion. This media can be read by the computer, stored inthe memory, and executed by the processor. As used herein, acomputer-readable storage medium excludes any computer-readable media onwhich signals may be propagated. However, a computer-readable storagemedium may include internal signal traces and/or internal signal pathscarrying electrical signals therein

Any references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

For the purposes of promoting an understanding of the principles of theinvention, reference has been made to the embodiments illustrated in thedrawings, and specific language has been used to describe theseembodiments. However, no limitation of the scope of the invention isintended by this specific language, and the invention should beconstrued to encompass all embodiments that would normally occur to oneof ordinary skill in the art.

The invention may be described in terms of functional block componentsand various processing steps. Such functional blocks may be realized byany number of hardware and/or software components configured to performthe specified functions. For example, the invention may employ variousintegrated circuit components, e.g., memory elements, processingelements, logic elements, look-up tables, and the like, which may carryout a variety of functions under the control of one or moremicroprocessors or other control devices. Similarly, where the elementsof the invention are implemented using software programming or softwareelements the invention may be implemented with any programming orscripting language such as C, C++, Java, assembler, or the like, withthe various algorithms being implemented with any combination of datastructures, objects, processes, routines or other programming elements.Functional aspects may be implemented in algorithms that execute on oneor more processors. Furthermore, the invention could employ any numberof conventional techniques for electronics configuration, signalprocessing and/or control, data processing and the like. The words“mechanism” and “element” are used broadly and are not limited tomechanical or physical embodiments, but can include software routines inconjunction with processors, etc.

The particular implementations shown and described herein areillustrative examples of the invention and are not intended to otherwiselimit the scope of the invention in any way. For the sake of brevity,conventional electronics, control systems, software development andother functional aspects of the systems (and components of theindividual operating components of the systems) may not be described indetail. Furthermore, the connecting lines, or connectors shown in thevarious presented are intended to represent exemplary functionalrelationships and/or physical or logical couplings between the variouselements. It should be noted that many alternative or additionalfunctional relationships, physical connections or logical connectionsmay be present in a practical device. Moreover, no item or component isessential to the practice of the invention unless the element isspecifically described as “essential” or “critical”.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural. Furthermore, recitation of ranges of values herein are merelyintended to serve as a shorthand method of referring individually toeach separate value falling within the range, unless otherwise indicatedherein, and each separate value is incorporated into the specificationas if it were individually recited herein. Finally, the steps of allmethods described herein can be performed in any suitable order unlessotherwise indicated herein or otherwise clearly contradicted by context.The use of any and all examples, or exemplary language (e.g., “such as”or “for example”) provided herein, is intended merely to betterilluminate the invention and does not pose a limitation on the scope ofthe invention unless otherwise claimed. Numerous modifications andadaptations will be readily apparent to those skilled in this artwithout departing from the spirit and scope of the invention.

According to the embodiments of the invention, 5-magnification opticalzooming can be implemented using a 2-step zoom lens barrel assembly thatunfolds a first zoom ring and a second cylinder in 2 steps, and thus the2-step zoom lens barrel assembly has a reduced number of parts. Further,the number of relatively moving barrels is reduced, and thus a zoom lensbarrel assembly having a small thickness or short length is realizedwhen the zoom lens barrel assembly is accommodated in an optical devicesuch as a camera.

While the invention has been particularly shown and described withreference to exemplary embodiments thereof, it will be understood bythose of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the invention as defined by the following claims.

1. A zoom lens barrel assembly comprising: a first zoom ring forsupporting a first lens group and comprising a first protrusionprotruding outward; a guide ring comprising a first guide slot extendingin an axial direction, through which the first protrusion passes, and asecond guide slot extending in a circumferential direction, and disposedaround the first zoom ring; a second zoom ring for supporting a secondlens group, comprising a second protrusion protruding outward, andmovably disposed in the axial direction with respect to the first zoomring; a first cylinder comprising a second zoom ring guide groove formedin an inner wall surface of the first cylinder into which the secondprotrusion is inserted and a third protrusion protruding outward so asto pass through the second guide slot, and disposed between the firstzoom ring and the second zoom ring so as to rotate and move in the axialdirection; a second cylinder comprising a fourth protrusion protrudingoutward, rotatably disposed around the guide ring, comprising a firstgroove portion into which the first protrusion passing through the firstguide slot is inserted, and a second groove portion into which the thirdprotrusion passing through the second guide slot is inserted, andmovably supporting the first zoom ring and the first cylinder; and anexternal cylinder comprising a third groove portion into which thefourth protrusion is inserted, and disposed around the second cylinderto rotatably support the second cylinder.
 2. The zoom lens barrelassembly of claim 1, further comprising: a guide portion disposedguiding a motion of the second zoom ring in the axial direction whilethe first cylinder rotates.
 3. The zoom lens barrel assembly of claim 2,wherein the second zoom ring further comprises a cutting portionextending in the axial direction in the outside thereof, and the guideportion is disposed between the second zoom ring and the first cylinder,coupled to the cutting portion, and guides a motion of the second zoomring in the axial direction.
 4. The zoom lens barrel assembly of claim2, wherein the second zoom ring further comprises a guide slot extendingin the axial direction, and the guide portion is pin-shaped extending inthe axial direction, inserted into the guide slot, and guides a motionof the second zoom ring in the axial direction.
 5. The zoom lens barrelassembly of claim 1, wherein the second cylinder further comprises agear disposed around the second cylinder and extending in thecircumferential direction, and the zoom lens barrel assembly furthercomprises a driving portion coupled to the gear and for generating adriving force used to rotate the second cylinder.
 6. The zoom lensbarrel assembly of claim 1, further comprising: a base fixed to theexternal cylinder; and an optical device disposed in the base so thatthe optical device corresponds to the first lens group and the secondlens group.
 7. The zoom lens barrel assembly of claim 6, furthercomprising: a third lens group disposed between the optical device andthe second lens group; a third zoom ring for supporting the third lensgroup and moving in the axial direction; and a focus driving unitcoupled to the third zoom ring and generating a driving force.
 8. Thezoom lens barrel assembly of claim 7, wherein the second groove portionextends in the axial direction, and the second guide slot comprises asustaining portion extending in the circumferential direction parallelto a boundary of one end of the guide ring and sustaining a position ofthe first cylinder in the axial direction with respect to the guidering, and a changing portion inclined from an end portion of thesustaining portion toward a boundary of another end of the guide ringand for changing the position of the first cylinder in the axialdirection with respect to the guide ring.
 9. The zoom lens barrelassembly of claim 8, wherein the first groove portion comprises a firstinclination portion inclined from a boundary of one end of the secondcylinder toward a boundary of another end thereof, extending in thecircumferential direction, and moving the first zoom ring forward in theaxial direction with respect to the second cylinder, and a secondinclination portion inclined from an end portion of the firstinclination portion toward the boundary of the one end, extending in thecircumferential direction, and moving the first zoom ring backward inthe axial direction with respect to the second cylinder.
 10. The zoomlens barrel assembly of claim 9, wherein the second zoom ring guidegroove comprises a rectilinear portion rectilinearly extending in theaxial direction from a boundary of one end of the first cylinder towarda boundary of another end thereof, a backward inclination portioninclined from an end portion of the rectilinear portion toward theboundary of the one end of the first cylinder, extending in thecircumferential direction, and moving the second zoom ring forward inthe axial direction with respect to the first cylinder, and a forwardinclination portion inclined from the backward inclination portiontoward the boundary of the other end of the first cylinder, extending inthe circumferential direction, and moving the second zoom ring forwardin the axial direction with respect to the first cylinder.